I does appear that I have somehow slapped your proverbial puppy. I do not know if you are being obtuse or you are incapable of understanding what I have written because your counter argument is disjointed and your understanding of gas exchange and SNS is lacking. First off, nowhere in the description of my method do I state that the starter needs to be shaken periodically. I challenge you to find any text where I make claim. Secondly, CO2 naturally comes out of solution at room temperature. Anyone who has pulled an over-gassed pint from a cold keg has experienced the massive foaming that occurs as CO2 gas rapidly comes out of solution. The only way to prevent out gassing at room temperature is via pressure. A starter continues to outgas CO2 even when a airlock is attached. However, nowhere in my method do I discuss using an air lock. I have always used a container that has a screw-on cap. All one has to do after shaking is loosen the cap.
As far to the use of an impeller in a bioreactor, that is not the way it is used in continuous propagation. The impeller is not used as much to drive off CO2 as it is to keep the medium at a steady state (Google “steady state condition”). Yeast and spent medium are continuously drawn off on the discharge end while new medium and O2 are continuously added to the process on the intake end; therefore, CO2 has a way to escape solution.
In the end, no one in this thread has mentioned that you need to switch propagation methods, no one. This thread has been about the belief that stir plates are the best way to make starters being myth. On the other, you joined the discussion apparently itching for a fight. As I mentioned above, it is like I slapped your proverbial puppy when all I did was present facts that are backed up by peer-reviewed science, science that has stood the test of time and has been built upon by other professional scientists. I have been studying brewing yeast for a long time, seriously for at least a decade. I brewed almost exclusively with yeast I isolated and maintained on agar slants for my first and second passes through the hobby, which means I have a pretty good understanding of yeast management. I did not start out to prove that stir plate mania was myth. It is just that as an INTJ (Myers-Briggs type), I have an insatiable thirst for knowledge. Brewing yeast has fascinated me for close to thirty years. The results that I achieved using a stir plate did not align with the hype, given my previous experience with other methods. That is what caused me to question the use of stir plates in the amateur brewing community.